Method of constructing ships

ABSTRACT

Method of constructing ships, at yard level as contrated with constructing ships within a dock. The method includes building individual sections at yard level, longitudinally aligning and advancing the sections towards a semi-graving dock, pivoting the ships sections from yard level onto the inclined grade of the semi-graving dock, integrating by welding the sections with respect to each other and as a ship within the semi-graving dock, and launching the ship stern first from the semi-graving dock.

United States Patent [1 1 Weise et al.

METHOD OF CONSTRUCTING SHIPS Inventors: Gary V. Weise, Newport; Richard C.

Moore, Hampton; James C. Sweat, Newport News, all of Va.

Newport News Shipbuilding and Dry Dock Company, Newport News, Va.

Filed: July 15, 1971 App1.No.: 162,901

Assignee:

References Cited UNITED STATES PATENTS 12/1943 Harris 114/65 R 12/1961 Svensson 114/65 R 2/1968 Muto et a1. 114/65 R 2/1969 Suit 114/65 R 6/1969 Myers 114/65 R 11/1969 l-loeven 114/65 R 1451 July 3, 1973 3,698,344 10/1972 Maeda 114/77 R FOREIGN PATENTS OR APPLICATIONS 623,186 5/1949 Great Britain 114/65 R 679,927 9/1952 Great Britain 836,609 4/1952 Germany 114/65 R Primary Examiner-Milton Buchler Assistant Examiner-Jesus D. Sotelo Attorney-David H. Semmes [57] ABSTRACT Method of constructing ships, at yard level as contrated with constructing ships within a clock. The method includes building individual sections at yard level, longitudinally aligning and advancing the sections towards a semi-gra ing dock, pivoting the ships sections from yard level onto the inclined grade of the semi-graving dock, integrating by welding the sections with respect to each other and as a' ship within the semi-graving dock, and launching the ship stern first from the semigraving clock.

3 Claims, 9 Drawing Figures PAIENIEUJULB ms 3.742.889

' saw 1 or 3 INKVENTORS GARY V. WEISE RICHARD MOORE C. JAMES C. SWEAT BY MMflZ JJwiW ATTORNEY wk H. a N \w\ w. M. a Y 6 Q PATENTEBJuLa ms SHEEP 2 BF 3 s E R m m H mm E E mw w E S WDC. vm E WWM mm um m ATTORNEY PAIENTEDJULS 191a 3.742.889 srmafl s INVENTORS GARY V WEISE RICHARD C. MOORE JAMES C. SWEAT ATTORNEY METHOD OF CONSTRUCTING SHIPS BACKGROUND OF THE INVENTION 1. Field of the Invention A great deal of recent attention has been given to shipbuilding methods which eliminate conventional construction difficulties, as well as reduce the capital investment required in drydock construction. For example, drydock construction requires a concentration of shipbuilding activity within a relatively inaccessible area with consequent loss in worker efficiency. The confined environment of the drydock, as well as the necessity for elevator transport of workers contribute to increased labor costs, apart from theprodigious capital investment required in the drydock facility. Accordingly, some inventors have addressed themselves to techniques involving the assembly of ships sections at yard level, thence transport of the individual sections into a graving dock or drydock for integration of the sections as a ship.

2. Description of the Prior Art Smith U.S. Pat. No. 2,334,794; Svensson U.S. Pat. No. 3,011,252; Muto, et al. U.S. Pat. No. 3,370,563; Myers U.S. Pat. No. 3,447,503; Foster U.S. Pat. No. 3,478,526; and West Germany Pat. No. 836,609.

The above-identified inventors have attempted several innovations in construction of ship sections. For example, Muto, et al., construct their ship in two sections, launch the sections and then weld the bow and stern sections together within the water. The difiiculties of welding within the marine environment are manifest. Myers Great Lakes ore carriers are constructed from modules. Myers bow section is launched, .and a customized water tight and floating dock 30 is fitted to the bow. Myers individual modular sections are assembled within the floating dock (FIG. 3) and then are pivoted horizontally (FIGS. 4 and 5) for integration with respect to each other.

Svensson assembles individual ship sections within a shelter or hall 8. Note, for example, Svenssons stern and bow sections under construction in FIG. 1. The individual sections are then integrated to each other upon an inclined way. A principal shortcoming is that Svenssons construction needs be carried out upon an incline and, again, within the relatively small confines of the expensive shelter 8.

West Germany Pat. No. 836,609, discloses an elaborate elevated drydock device 8 (FIGS. 3 and 4) which is lifted from yard level to water level, as construction is completed. The size and weight of contemporary commercial ships would preclude use of the West Germany Pat. No. 836,609 device.

Smith and Foster were selected as showing types of pivoting devices used for launching ship sections, so as to avoid the risks inherent in the conventional sidewise launch.

SUMMARY OF THE INVENTION According to the applicants method, a yard level or yard grade ship construction area and an inclined semigraving dock may be axially aligned and a pivoting platform is interposed between yard level and the semigraving dock incline. The individual shipsections may be constructed upon wheeled cars mounted upon rails which extend through the yard level construction area, pivoting platform and into the semi-graving dock. The cars supporting the completed ship sections are advanced from yard level onto the pivoting platform, where they are pivoted from yard level onto the incline of the semi-graving dock and then moved into it. The ship sections are integrated, such as by welding, upon the incline, and may be supported by conventional blocks. The ship may be ballasted prior to, or during dock flooding, so as to maintain the ship parallel with the graded incline. When flooding is completed, the ship is floating and will be removed stern first from the semi-graving dock with minimum risk.

Apartfrom the manifest economies of yard level construction, a a minimum capital investment is required, since the translation of the completed ship sections from yard level to semi-graving dock is relatively simply effected. Also, the costs of constructing the semigraving dock, the yard level construction area and pivoting platform are less than the cost of constructing conventional dry dock facilities of equal production capacity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, is a side elevation, showing from right to left the yard level building area, the intermediate pivoting ramp and the inclined semi-graving dock which is used for integration of the ship sections, as well as launching and repair of the completed ship;

FIG. 2, is a top plan thereof;

FIG. 3, is a transverse section taken along section line 3-3 of FIG. 2;

FIG. 4, is a fragmentary perspective, showing the pivoting ramp with respect to the inclined semi-graving dock, The ramp being pivotable on either an end or middle pivot.

FIG. 5, is a side elevation, showing an individual ship section being pivoted upon a ramp having a middle pivot bearing;

FIG. 6, is a similar side elevation, showing a ship section pivoted upon a ramp having an end pivot bearing; and

FIG. 7, is similar elevation showing end pivot and ramp on yard grade;

FIG. 8, is a side elevation of a wheeled carrier or car for constructing and advancing individual ship sections;

FIG. 9, is a fragmentary top plan, similar to FIG. 2, showing the individual ship sections being constructed laterally apart from the translation area into which they are moved transversely and prior to longitudinal advancement through the pivoting ramp and onto the inclined floor of the semi-graving dock.

DESCRIPTION OF THE PREFERRED EMBODIMENTS combined. The pivoting ramp platform permits the heaviest loads contemplated in shipbuilding to be transferred to the grade of the semi-graving dock since it all but eliminates unsupported structural spans and enables changing the grade of assemblies of the size associated with the present and future generations of large commercial ships. Also, there is the inherent mechanical advantage associated with a pivoting ramp which reduces the power requirements needed to move it. The pivoting ramp is constrained by a hinge at the pivot point and pivoted by a mechanical or hydraulic device. Such variables as semi-graving dock floor incline and overall size can be adjusted to optimize facility construction and operating costs with ship size and production rate requirements. The yard grade construction area, the semi-graving dock floor and the pivoting ramp contain one of the many types of translation systems, such as tracks and dollies, incorporated in their structures. Thus, ship sections can be built complete at yard grade, unconstrained by space and many other of the traditional detrimental shipbuilding environment limitations, to the dimensions of final ship depth and beam. In this manner the work required to take place in the semi-graving dock can be reduced to the mere integration of ship sections and thus a much higher production rate can be realized than in a conventional graving dock without the pivoting ramp and translation systems. It is contemplated that ships will usually be constructed in the semi-graving dock stern to the gate as they are usually stern-heavy at this stage of construction because of the machinery there, and this will facilitate ballasting the ship to the grade of the dock floor. This in turn is necessary to insure that no damage will occur during undocking. The ships will be floated on and off of supports as in conventional graving dock procedure.

Several configurations of the pivoting ramp are possible as shown in FIGS. 5, 6, and 7. In either case, the load of the ship part being moved is carried by the pivoting point and the pivoting mechanism (i.e. jack, hydraulic cylinders, rack and pinion, worm gear, opposed chain falls, etc.). The grid work of the ramp may be constructed so as to limit deflections of the ramp to a minimum acceptable tolerance at maximum load.

The translation system is designed to allow for bracing and holding of loads on the inclined floor of the semi-graving dock. Capability to move the loads up the shipway is also necessary to allow positioning during the integration phase of ship construction.

Unlike most new shipbuilding methods, the semigraving dock/pivoting ramp method offers the additional advantage of permitting the shipbuilder to make use of existing facilities and production methods while making improvements on an incremental basis. Initially a large semi-graving dock can be built and ships constructed in a nearly conventional manner. The pivoting ramp could be added at a later date to permit the more efficient construction of engine rooms above ground while mid-bodies and bows are still constructed in the conventional manner. At a still later date, aboveground ship section construction areas could be added thus moving all but the integration construction work up out of the dock on to yard grade.

FIGS. 1 and 2 depict the axial alignment of yard level construction area 10, pivoting ramp l2 and semigraving dock 14 having an inclined floor for integration, repair and launch of a vessel. Semi-graving dock 14 may be provided with an end gate 20 extending, for example 8 feet above mean high water and dock walls 66 and 64 upon which a 50-ton gantry 16 may be employed. Such provisions allow for the capability of performing ship repair or recovery work simultaneously with new ship construction. This is possible because of the relatively short time required to integrate ship sections as opposed to building them. A series of rails 18 may extend from the yard level erection area 10 through pivoting ramp 12 and into the semi-graving dock 14. The individual ship sections: 34, 36, 38, 40, 42, 44, 46, 48, 50, 52 and 54 may be constructed at yard level upon the wheeled cars of the type 32 illustrated in FIG. 8. Such cars 32 may have pairs of fore and aft wheels 72 and 74, engaging rails 18. In FIG. 8, stern section 34 is shown, for example, supported upon conventional shoring elements 76. The cars may be self-propelled or may be propelled by other means well known in the art. The whirler cranes 22, 24, 26 and 28 may be used in constructing the ship sections and may travel upon tracks -82 and 84-86 mounted at either side of the yard level assembly area. Also large gantry cranes 55 may be employed to assist in construction and handling of the ship sections, for example, positioning of superstructure 31 upon stern well 34.

Manifestly, the cars 32, the number and type of cranes, the mechanics of advancing, pivoting such as upon medial pivot 70, or end pivots 71 and 73, as well as supporting the ship sections may be varied without departing from the spirit of the invention.

We claim:

1. Method of constructing ships by assembling a plurality of longitudinally aligned ship sections comprising:

A. completely building all individual hull sections at yard level prior to assembling;

B. longitudinally advancing said completed hull sections along said yard and towards a lower semigraving dock of the type having an inclined floor;

C. pivoting downwardly said hull sections upon a transverse axis during advancing, so as to guide longitudinally said sections from yard level onto said inclined floor;

D. assembling said hull sections with respect to each other and as a ship upon said inclined floor; and

E. launching said ship from said semi-graving dock.

2. Method of constructing ships from a plurality of longitudinally aligned ship sections as in claim 1, including building of individual ship sections at yard level on one side of said semi-graving dock, and transversely moving said sections into axial alignment with said semi-graving dock at yard level prior to longitudinally advancing and pivoting into said semi-graving dock.

3. Method of constructing ships from a plurality of longitudinally aligned ship sections as in claim 2, including confining and repairing another ship within said semi-graving dock while building and longitudinally advancing and pivoting individual ship sections in said yard level.

i t i i i 

1. Method of constructing ships by assembling a plurality of longitudinally aligned ship sections comprising: A. completely building all individual hull sections at yard level prior to assembling; B. longitudinally advancing said completed hull sections along said yard and towards a lower semi-graving dock of the type having an inclined floor; C. pivoting downwardly said hull sections upon a transverse axis during advancing, so as to guide longitudinally said sections from yard level onto said inclined floor; D. assembling said hull sections with respect to each other and as a ship upon said inclined floor; and E. launching said ship from said semi-graving dock.
 2. Method of constructing ships from a plurality of longitudinally aligned ship sections as in claim 1, including building of individual ship sections at yard level on one side of said semi-graving dock, and transversely moving said sections into axial alignment with said semi-graving dock at yard level prior to longitudinally advancing and pivoting into said semi-graving dock.
 3. Method of constructing ships from a plurality of longitudinally aligned ship sections as in claim 2, including confining and repairing another ship within said semi-graving dock while building and longitudinally advancing and pivoting individual ship sections in said yard level. 